Lapping machine

ABSTRACT

A LAPPING MACHINE WHEREIN A SINGLE RING-SHAPED ROTARY LAP SUPPORTS SEVERAL RING-SHAPED ADAPTORS WHICH ACCOMMODATE WORK HOLDERS FOR WORKPIECES RESTING ON THE LAPPING SURFACE OF THE LAP. THE ADAPTORS HELD AGAINST ROTATION WITH THE LAP BY A DISK WHICH IS COAXIAL WITH THE LAP AND BY ONE OR MORE ROLLERS WHICH ARE MOUNTED ON ARMS CARRIED BY THE FRAME OF THE LAPPING MACHINE. THE PERIPHERAL SURFACE OF EACH ADAPTOR ABUTS AGAINST THE DISK AND AGAINST THE RESPECTIVE ROLLER OR ROLLERS. THE AXIAL POSITION OF THE DISK AND/OR THE AXIAL POSITIONS OF THE ROLLERS ARE ADJUSTABLE TO THEREBY CHANGE THE PRESSURE BETWEEN THE WORKPIECES AND THE INNER OR OUTER PORTIONS OF THE LAPPING SURFACE. IN THIS WAY, UNEVEN WEAR ON SELECTED PORTION OR PORTIONS OF THE LAPPING SURFACE CAN BE ELIMINATED OR INTENTIONALLY BROUGHT ABOUT BY APPROPRIATE ADJUSTMENT OF THE DISK AND/OR ROLLERS.

March 16, 1971 H. EBNER LAPPING MACHINE 3 Sheets-Sheet 1 Filed April 12, 1968 Fig.2

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March 16, 1971 H. EBNER LAPPING MACHINE 3 Sheets-Sheet 2 Filed April 12, 1968 Fig. I

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LAPPING MACHINE Filed April 12, 1968 3 Sheets- Sheet 5 Fig.5

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Arron/v67 United States Patent O 3,570,188 LAPPING MACHINE Hellmut Ebner, Mettmann, Rhineland, Germany, assignor to Peter Wolters Kratzenfabrik und Maschinenfabrik, Mettmann, Germany Filed Apr. 12, 1968, Ser. No. 720,922 Claims priority, application Germany, Apr. 15, 1967, W 43,767 Int. Cl. B24b 5/00 US. Cl. 51-129 13 Claims ABSTRACT OF THE DISCLOSURE A lapping machine wherein a single ring-shaped rotary lap supports several ring-shaped adaptors which accommodate work holders for workpieces resting on the lapping surface of the lap. The adaptors held against rotation with the lap by a disk which is coaxial with the lap and by one or more rollers which are mounted on arms carried by the frame of the lapping machine. The peripheral surface of each adaptor abuts against the disk and against the respective roller or rollers. The axial position of the disk and/or the axial positions of the rollers are adjustable to thereby change the pressure between the workpieces and the inner or outer portions of the lapping surface. In this way, uneven wear on selected portion or portions of the lapping surface can be eliminated or intentionally brought about by appropriate adjustment of the disk and/or rollers.

BACKGROUND OF THE INVENTION The present invention relates to lapping, grinding, polishing or like superfinishing machines in general, and more particularly to improvements in lapping or like machines having a single lap.

It is already known to provide a lapping machine with a single rotary lap whose lapping surface supports several workpieces which are confined in suitable work holders. When the lap rotates, the wear on the outer portion of its lapping surface often exceeds the wear on the inner portion or vice versa, i.e., the wear upon the lapping surface at different distances from the axis of the lap is not uniform. Uneven lap wear can be compensated for by adaptors which accommodate the work holders by changing the rotational speed and/or the direction of rotation of one or more adaptors or by changing the pressure with which the adaptors bear against the lapping surface. All such adjustments are rather complicated and the extent to which the uneven wear is reduced cannot be readily determined in advance.

SUMMARY OF THE INVENTION It is an object of my invention to provide a lapping machine wherein the wear upon different portions of the lapping surface on a single rotary lap can be adjusted, equalized or intentionally changed in a simple way, by resorting to simple parts, and in a timeand space-saving manner.

Another object of the invention is to provide a lapping machine wherein the pressure with which different portions of one or more adaptors and their contents bear against selected portions of the lapping surface can be regulated with a high degree of precision.

A further object of the invention is to provide the lapping machine with a novel blocking arrangement for holding one or more adaptors against rotation with the lap and for simultaneously determining the wear on selected portions of the lapping surface.

An additional object of the invention is to provide a lapping machine wherein the lapping surface may be 3,570,188 Patented Mar. 16, 1971 intentionally corrected to assume a truly horizontal, concave or convex shape and wherein such correction can be carried out by parts which are necessary for proper treatment of workpieces in the machine.

The invention is embodied in a lapping or like machine which comprises a single lap rotatable in or on a support about a preferably vertical axis and has a lapping surface which is the top surface of the lap, at least one workaccommodating adaptor or retainer which preferably resembles a ring and rests on the lapping surface, and novel blocking means for holding the adaptor against rotation with the lap about the latters axis. The blocking means comprises first stop means engaging the peripheral surface of the adaptor at a point located at a first distance from the lap axis and at least one second stop means engaging the peripheral surface of the adaptor at a point which is located at a greater second distance from the lap axis. At least one of the stop means is adjustable in a direction at right angles to the lapping surface, preferably in the axial direction of the lap, so that the two stop means can subject the adaptor to more or less pronounced tilting stresses whereby the adaptor and its contents exert a greater or lesser pressure upon selected portions of the lapping surface. In this way, the wear upon all portions of the lapping surface can be equalized or the operator can intentionally subject a selected portion of the lapping surface to greater or lesser wear. The first stop means may comprise a single disk-shaped stop member which is coaxial with and is movable axially of the lap, and the second stop means may comprise one or more rollers which are adjustable in the axial direction of the lap and are preferably adjustable also in the radial and/ or circumferential direction of the lap.

The novel features which are considered as characteristic of the invention are set forth in particular in the appended claims. The improved lapping machine itself, however, both as to its construction and its mode of operation, together with additional features and advantages thereof, will be best understood upon perusal of the following detailed description of certain specific embodiments with reference to the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a perspective view of a lapping machine which embodies one form of the invention;

FIG. 2 is an enlarged fragmentary axial sectional view of the lapping machine;

FIG. 3 is a similar fragmentary axial sectional view of a second lapping machine;

FIG. 4 is a fragmentary top plan view of a third lapping machine; and

FIG. 5 is a sectional view as seen in the direction of arrows from the line VV of FIG. 4.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The lapping machine of FIGS. 1 and 2 comprises a single annular lap 3 having a ring-shaped lapping surface and secured to a rotary turntable or carrier 2 by way of screws 4. The carrier 2 is rotatably mounted in the frame or base 1 of the lapping machine and is driven to rotate about a vertical axis. The lapping surface is the upper surface of the lap 3 and is located in a horizontal plane. A plate-like centrally located portion of the carrier 2 supports an upwardly extending shaft 5 which is coaxial therewith and is atfixed thereto by a key so that it shares all angular movements of the lap 3. The shaft 5 supports a disk-shaped inner stop member 6 which is non-rotatably but axially movably secured thereto by a key 16. A locking screw .17 can be tightened to fix the disk 6 in a selected axial position on the shaft 5. This disk is adjustable on the shaft 5 in a direction at right angles to the lapping surface, i.e., along the common axis of the carrier 2 and lap 3. The frame 1 supports three upwardly extending pivots 8 which define vertical pivot axes for supports or arms 7. Each of these arms 7 can be fixed in selected angular position, for example, by means of screws similar to the locking screw 17. The arms 7 are located at a level above the lap 3 and their free ends carry downwardly extending shafts 9 for roller-shaped outer stop members which constitute the outer races of antifriction bearings. It is clear that the rollers 10 can be mounted on the outer races of the respective bearings. The lapping surface of the lap 3 supports three ring-shaped adaptors or retainers 11 each of which accommodates a plate-like work holder 13 having apertures for several workpieces 12 whose undersides rest on the lapping surface.

If desired or necessary, a special weight 14 can be placed on top of each work holder 13. Furthermore, a cushion of felt or the like can be interposed between each weight 14 and the respective Work holder 13 in order to compensate for eventual differences in the height of workpieces 12 which are accommodated in the apertures of such work holder.

When the carrier 2 receives torque from an electric motor (not shown) or another suitable prime mover, it rotates the lap 3 and the shaft 5. The shaft 5 transmits torque to the disk 6 which rotates in the same direction as the lap 3. The peripheral surfaces of the adaptors 11 abut against the peripheral surface of the disk 6 and are thus set in rotary motion in response to friction between the respective peripheral surfaces. The rollers 10 hold the respective adaptors 11 against rotation with the lap 3 about the axis of the carrier 2. It is to be noted that the rollers 10 are mounted on arms 7 which are secured to the stationary frame 1 of the lapping machine. If the adaptors 11 were not rotated by the disk 6, they would be rotated by the lap 3 but in the opposite direction. The friction between the adaptors 11 and the disk 6 must be sufficient to overcome the tendency of the adaptors to rotate in the opposite direction.

If the lapping surface of the lap 3 happens to wear away mainly along its inner portion, i.e., in the region close to the vertical axis of the carrier 2, so that the wear on the inner portion of the lapping surface is more pronounced than on the outer portion of this surface, the operator moves the disk 6 to a higher level. This is achieved by releasing the locking screw 17 and by thereupon shifting the disk 6 upwardly along the shaft *5 and key 16. The screw 17 is then tightened again to fix the disk 6 in the newly selected adjusted axial position. For example, the disk 6 can be moved to the position which is indicated in FIG. 2 by phantom lines. The adaptors 11 are then acted upon by two forces (produced by the disk 6 and the corresponding rings 10) which tend to tilt the adaptors in a sense to lift their inner portions off the lapping surface. Thus, the pressure which is applied to the outer portion of the lapping surface exceeds the pressure which is applied to the inner portion of the lapping surface so that the outer portion wears away more rapidly and the lapping surface undergoes a truing or redressing operation while the lapping machine is in actual use and without resorting to any special truing or redressing devices.

If the wear on the outer portion of the lapping surface exceeds the wear upon the inner portion, the disk 6 is moved downwardly, for example, to the phantom-line position 24 of FIG. 2, so that the adaptors 11 are again subjected to tilting stresses but in the opposite direction, i.e., the pressure upon the inner portion of the lapping surface exceeds the pressure upon the outer portion and the inner portion wears away more rapidly than the outer portion.

R is further clear that the disk 6 can be moved to the position 24 or 25 prior to start of the lapping operation, i.e., when the lapping surface is still absolutely flat. This is done if the operator knows in advance that, in lapping of a particular type or group of workpieces, the inner portion of the lapping surface will wear away more rapidly than the outer portion or vice versa. Otherwise, the disk 6 is initially fixed in the median or neutral position which is shown in FIG. 2 by solid lines. The disk 6 can be moved from such neutral position if the operator wishes to impart to the lapping surface a slightly concave or convex outline. It is further clear that the same results can be achieved by changing the axial positions of the rollers :10; however, it is normally preferred to adjust the disk 6 because a single adjustment then suffices to change the pressures which are applied to the inner or outer portion of the lapping surface.

I he magnitude of forces which act upon the lapping surface can be changed in still another way, namely, by adjusting the distance between the disk 6 and one or more rollers 10. If the distance between the disk 6 and the rollers 10 is increased, i.e., if the operator lengthens the shortest distance between the points at which the peripheral surface of an adaptor 11 engages with the disk 6 and with the corresponding roller .10, the magni tude of forces acting upon the adaptor increases and the workpieces 12 then cause a more pronounced wear upon the inner or outer portion of the lapping surface, depending on the axial position of the inner ring 6. Otherwise stated, by turning the supports or arms 7 about the respective pivots 8, the operator can change the angle between the lines which connect the axis of the lap 3 with the axes of the adaptors 11 and the lines which connect the points where the respective adaptors engage the disk 6 and the associated rollers 10.

The weight 14 is provided with a radially outwardly extending post or stud 26 which extends into an axially parallel internal groove 27 of the adaptor ].-1 shown in FIG. 2 to prevent relative angular displacement between the weight and the adaptor.

FIG. 3 illustrates a portion of a second lapping machine wherein the lap 3 is mounted and driven in the same way as in the machine of FIGS. 1 and 2. The mounting of supports or holders 7 and outer stop members or rollers 10 is also the same. The disk-shaped inner stop member 6 is replaced by a similar stop member 21 which is freely rotatable on an adjusting sleeve 18 which is non-rotatably but axially movably coupled to the shaft 5 of the carrier 2 by a key 20. The sleeve 18 supports a coaxial spindle 19 which is rotatable with reference thereto and is externally threaded at 1% to mesh with internal threads provided in a tapped bore of the shaft 5. The upper end of the spindle 19 carries an adjusting knob 19a which can be manipulated by hand in order to change the axial position of the sleeve 18 and inner stop member 21 with reference to the adaptor or adaptors 11 and shaft 5. The lower end of the sleeve 19 carries a flange 22 which abuts against the lower end face of the stop member 21. The upper end face of this stop member abuts against a collar 23 on the sleeve 18 so that the stop member 21 is held against axial movement with reference to the sleeve. The main difference between the machine of FIGS. 1-2 and the machine of FIG. 3 is that the inner stop member 21 is free to rotate with reference to the lap 3. The numerals 24 and 25 again denote two different axial positions of the stop member 21.

Referring now to FIGS. 4 and 5, there is shown a portion of a third lapping machine wherein the mounting of the lap 3, of the disk-shaped inner stop member 6 and of the support or holder 7 for a roller-shaped outer stop member 28 are the same as described in connection with FIGS. 1 and 2. The pivot 8 for the support or arm 7 carries a second support or arm 29 for a housing 33 which accommodates a horizontal shaft 30 which is axially movable therein and extend substantially radially of the adjoining ring-shaped adaptor 11. The shaft 30 has an axially parallel peripheral groove 37 for the ti of a screw 36 which is screwed into the housing 33 and holds the shaft 30 against rotation. The inner end portion of the shaft 30 has a head or boss 31 for a vertical shaft 32 which carries a third roller-shaped stop member engaging the peripheral surface of the adaptor 11. The roller 10 is preferably rotatable on or constitutes the outer race of an antifriction hearing. The housing 33 accommodates a helical resilient element 34 which biases the shaft radially inwardly and whose bias can be adjusted by a screw 35.

The arm 7 is adjustable about the axis of the pivot 8 and can be fixed in selected angular position. The same applies for the arm 29. Furthermore, the arms 7, 29 are preferably adjustable in the axial direction of the pivot 8, i.e., at right angles to the horizontal plane of the lapping surface.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge, readily adapt it for various applications without omitting features which fairly constitute essential characteristics of the generic and specific aspects of my contribution to the art and, therefore, such adaptations should and are intended to be comprehended with in the meaning and range of equivalence of the claims.

What is claimed as new and desired to be protected by Letters Patent is set forth in the appended claims:

1. A lapping machine comprising a lap rotatable about a predetermined axis and having a lapping surface; at least one work-accommodating adaptor on said lapping surface, said adaptor having a cylindrical outer surface of a predetermined height; and blocking means for holding said adaptor against rotation with the lap about said axis, said blocking means comprising first stop means engaging said cylindrical surface at a first distance from the axis of rotation of said lap and at a point located at one side of the axis of said adaptor and a second stop means engaging said cylindrical surface and located at a second distance from said axis of rotation and at the other side of said axis of said adaptor, at least one of said StOp means being adjustable with reference to said adaptor and the other stop means in a direction substantially at right angles to said lapping surface into a position vertically spaced from said other stop means to apply a tilting moment to said adaptor for reducing the pressure of said adaptor on said lapping surface adjacent the higher adjusted stop means.

2. A lapping machine as defined in claim 1, wherein said first stop means comprises a disk-shaped member coaxial with said lap and said second stop means comprises at least one roller-shaped member.

3. A lapping machine as defined in claim 2, wherein comprising at least one additional adaptor supported by said lapping surface and abutting against said disk-shaped member, and third stop means including at least one additional roller-shaped member spaced from said diskshaped member and engaging said additional adaptor.

4. A lapping machine as defined in claim 3, wherein 6 said disk-shaped member is adjustable in the aXial direction of said lap.

5. A lapping machine as defined in claim 3, wherein each of said roller-shaped members is adjustable in a di rection which is parallel to said axis.

6. A lapping machine as defined in claim 1, further comprising support means for said second stop means, said support means being movable between a plurality of positions in each of which said second stop means is located at a different distance from said first stop means.

7. A lapping machine as defined in claim 1, wherein said adaptor comprises a ring and further comprising support means for said second stop means, said support means being movable between a plurality of positions in each of which a line connecting the axes of said lap and said ring makes a different angle with a line connecting the points of engagement between said stop means and said ring.

8. A lapping machine as defined in claim 1, further comprising resilient means for biasing said second stop means against said adaptor and means for adjusting the bias of said resilient means.

9. A lapping machine as defined in claim 1, wherein said first stop means comprises a disk-shaped member which is coaxial with and is freely rotatable relative to said lap.

10. A lapping machine as defined in claim 1, wherein said axis is vertical and wherein said lapping surface is the upper surface of said lap and is located in a substantially horizontal plane, said adaptor comprising a ring and said first stop means comprising a disk-shaped member which is coaxial with said lap, said second stop means comprising at least one roller.

11. A lapping machine as defined in claim 1, wherein said first and said second stop means have cylindrical outer surfaces of a height smaller than said predetermined height of said cylindrical outer surface of said adaptor.

12. A lapping machine as defined in claim 11, wherein each of said first and second stop means is rotatable about its axis.

13. A lapping machine as defined in claim 1, wherein said adaptor is a ring and including weight means fitted in said ring movable in axial direction and adapted to engage work pieces located in said adaptor at a surface thereof opposite from said lap surface so as to press the work pieces against said lapping surface.

References Cited UNITED STATES PATENTS 3,031,806 5/1962 Jones 51- -l29 2,839,877 6/1958 Boettcher 51'131 3,050,910 8/1962 Lichtenfeld 51-129 2,883,802 4/1959 Katzke 5l131X 3,431,683 3/1969 Wright 51-429 HAROLD D. WHITEHEAD, Primary Examiner 

